Abstract
A significant improvement in the creep properties of magnesium monolithic alloys at high temperatures can potentially be achieved through processing various magnesium metal matrix composites in which the matrix alloy is strengthened through the introduction of non-metallic fibres or particulates. In this work, a comparison between the creep behaviour and characteristics of an unreinforced high-strength creep-resistant QE22 matrix alloy and a QE22 alloy composite reinforced with 20 vol.% Al₂O₃ (Saffil) short fibres was performed. Constant stress tensile creep tests were carried out at 423, 473, and 523 K, and the applied stresses ranged from 10 to 200 MPa. The creep strengthening of the composite by reinforcement arises mainly from effective load transfer between matrix and fibres provided that no extensive debonding of the fibre/matrix interfaces or substantial breakage of fibres during creep exposure occur. However, the beneficial effect of reinforcement and the improved creep resistance of the composite is significantly influenced by the creep loading conditions.

Key words
magnesium alloy, composite, creep, transfer load, fibre/matrix debonding, fracture

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